query about EDNS UDP Packet

Gaurav Kansal gaurav.kansal at nic.in
Mon Dec 31 10:54:38 UTC 2012


I just want to test whether this limit is within my organization.

Is any method available by which I can check this?

 

Regards,

Gaurav Kansal

 

From: bind-users-bounces+gaurav.kansal=nic.in at lists.isc.org
[mailto:bind-users-bounces+gaurav.kansal=nic.in at lists.isc.org] On Behalf Of
Sten Carlsen
Sent: Monday, December 31, 2012 4:02 PM
To: bind-users at lists.isc.org
Subject: Re: query about EDNS UDP Packet

 

It means that something in your path limits packet size. That could likely
be a firewall or router with a "helpful" function to pass DNS packets on;
only it thinks that a DNS packet can only be 512 bytes long.

On 31/12/12 10:49, Gaurav Kansal wrote:

Hello Team,

 

I am getting too many entries for reducing the EDNS Packet size to 512 bytes
in my log file.

For Eg:

 

Dec 31 03:07:20 IPv6-DNS named[3769]: success resolving 'dns1.vps.net/A' (in
'vps.net'?) after reducing the advertised EDNS UDP packet size to 512 octets

Dec 31 03:07:21 IPv6-DNS named[3769]: success resolving
'ad.metanetwork.com/A' (in 'metanetwork.com'?) after reducing the advertised
EDNS UDP packet size to 512 octets

Dec 31 03:07:25 IPv6-DNS named[3769]: success resolving
'geo.admetanetwork.com/A' (in 'admetanetwork.com'?) after reducing the
advertised EDNS UDP packet size to 512 octets

Dec 31 03:07:31 IPv6-DNS named[3769]: success resolving
'tomcat.apache.org/A' (in 'apache.org'?) after reducing the advertised EDNS
UDP packet size to 512 octets

Dec 31 03:07:31 IPv6-DNS named[3769]: success resolving 'www.apache.org/A'
(in 'apache.org'?) after reducing the advertised EDNS UDP packet size to 512
octets

Dec 31 03:07:31 IPv6-DNS named[3769]: success resolving
'issues.apache.org/A' (in 'apache.org'?) after reducing the advertised EDNS
UDP packet size to 512 octets

Dec 31 03:07:34 IPv6-DNS named[3769]: success resolving
'ns1.zurich.surf.net/A' (in 'surf.net'?) after reducing the advertised EDNS
UDP packet size to 512 octets

Dec 31 03:07:34 IPv6-DNS named[3769]: success resolving
'ns2.surfnet.nl/AAAA' (in 'surfnet.nl'?) after reducing the advertised EDNS
UDP packet size to 512 octets

Dec 31 03:07:34 IPv6-DNS named[3769]: success resolving 'ns2.surfnet.nl/A'
(in 'surfnet.nl'?) after reducing the advertised EDNS UDP packet size to 512
octets

Dec 31 03:07:34 IPv6-DNS named[3769]: success resolving
'ns1.zurich.surf.net/AAAA' (in 'surf.net'?) after reducing the advertised
EDNS UDP packet size to 512 octets

Dec 31 03:07:34 IPv6-DNS named[3769]: success resolving './NS' (in '.'?)
after reducing the advertised EDNS UDP packet size to 512 octets

Dec 31 03:07:40 IPv6-DNS named[3769]: success resolving
'ns1.zurich.surf.net/A' (in 'surf.net'?) after reducing the advertised EDNS
UDP packet size to 512 octets

Dec 31 03:07:40 IPv6-DNS named[3769]: success resolving
'ns1.zurich.surf.net/AAAA' (in 'surf.net'?) after reducing the advertised
EDNS UDP packet size to 512 octets

 

On googling for this, I got to know that this come when remote DNS Server
doesn't support EDNS0 (i.e., packet size upto 4096 bytes).

 

Now I want to know whether my DNS Server supports EDNS0 for incoming request
or not.

I use the 'OARC's DNS Reply Size Test Server' for the same and I got the
below mentioned O/P:

 

#dig +short rs.dns-oarc.net txt

rst.x476.rs.dns-oarc.net.

rst.x450.x476.rs.dns-oarc.net.

rst.x490.x450.x476.rs.dns-oarc.net.

"Tested at 2012-12-31 09:40:11 UTC"

"164.100.1.206 sent EDNS buffer size 4096"

"164.100.1.206 DNS reply size limit is at least 490"

 

Does this mean that my server is not supporting EDNS0 ???

 

 

Thanks and Regards,

Gaurav Kansal

Mob - 9910118448

 

Happy New Year 2013.

IPv4 is Over,

Are your ready for new Network.

 






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-- 
Best regards
 
Sten Carlsen
 
No improvements come from shouting:
       "MALE BOVINE MANURE!!!"
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